AV Digital Content Creation / Media Encoding

Video and audio encoding are becoming increasingly important in the world of personal computing. Home-editing of videos and sound recordings are among the popular applications as is just the standard archiving of DVD material. In the case of audio encoding, there is relatively little out there in terms of applications that are multithreaded, meaning that they would take advantage of multiple cores. Or if there are appications like that, they are not free and the generally short conversion times achieved with free download utilities do not provide enough incentive to actually purchase potentially faster, multithreaded applications.For this article we used three applications namely DVD-Shrink 3.2, 8.1 (Nero Recode) and the latest version of MainConcept, namely H.264 Encoder.

In the case of DVD-Shrink we compressed John Grisham's "Runaway Jury" from 4,464 MB to 3,323MB, a compression to 59.6%. One caveat about DVD Shrink is that we found it is impossible to get relevant data points if the same physical drive is used for source and target files. In the fastest systems we have been looking at, the encoding rates were in excess of 50,000 kBytes/sec, which means that any sinble drive used as source and target would need to supply roughly 50 MB read bandwidth plus simultaneously some 50 MB write bandwidth. Aside from the issue of no current drive having that type of sustained internal transfer rate ( > 100 MB/sec), that situation would also be exacerbated by the switching between different folders for reads / writes, meaning that there would have to be platter and track switches that would further reduce the transfer rates.

We therefore used two separate drives in which the source folder and target files were placed into a dedicated partition at the OD of the drive. As a result, one drive was streaming source data to the system, the second drive was solely writing the data to the empty partition. The souce partition was defragmented before every run. By following this protocol, we largely eliminated I/O bottlenecks and as a result, DVD re-coding was improved on average by ~ 50% (e.g. 143 sec using two separate HDDs compared to 307 sec using a single physical drive). All data shown were obtained with the same protocol.

In the case of the Nehalem system we used Intel's SSD drive as source drive and saved the resulting compressed files on the C partition of the Maxtor drive. Switching the configuration resulted in a noticeable performance hit since media encoding writes relatively small files to the drive, which in the case of SSDs results in low write efficiency.

In the case of Nero 8.1 Recode, we used the same setup as for DVD-Shrink, that is,"Runaway Jury" and the source and target file folders were on physically separate drives to avoid I/O contention on either drive or interface level.

Mainconcept

In the case of MainConcept, we encoded a Watermellon.mpg file to an [H.264] High, 1920 x 1080 pixel, 29.97 fps, 48,000Hz 16 bit MPG file.